Vietnam took delivery of two new missile boats on Tuesday made locally and modeled on Russian vessels, the latest move by its military to strengthen maritime defenses as tensions simmer over sovereignty in the South China Sea.

The two Tarantul-class corvettes, known as Molniyas, are equipped with 16 missiles and automatic weapons and are among six ordered by the navy, two of which were delivered last year. The missiles have a range of 130 kilometers.

The announcement was carried on the Vietnamese government's news website and comes amid diplomatic rumblings over land reclamation work by rival claimants and United States concern over what it said was China's placement of mobile artillery systems in contested territory.

Vietnam's naval defense capabilities have been boosted by Russian hardware, including state-of-the-art kilo-class submarines recently equipped with a Russian land attack variant of the Klub missile. They are capable of precision strikes within a range of 300km.

Many experts see Vietnam's strengthening of its defenses and its diplomatic ties with Japan, the Philippines and the United States of late as signs of its determination to counter China's growing assertiveness after a bitter falling out with Beijing last year.

Deputy Defence Minister Truong Quang Khanh said the new boats showed Vietnam could "fully master the technology and techniques of modern military shipbuilding" and would boost its combat power and help protect its maritime sovereignty, according to the report.

It said the vessels could take on warships, amphibious ships and corvettes, protect submarines and carry out scouting.

China remains an important economic and political ally for Vietnam, but ties have been strained over competing claims to the Spratly and Paracel islands. China claims it has jurisdiction over nine-tenths of the South China Sea, putting it at odds with four Southeast Asian states.